1. Technical Field
The present disclosure relates generally to surgical instruments and, more particularly, to a laser ablation instrument having a fiber optic output tip which utilizes a micro-prism structure to deliver a uniform radial distribution pattern.
2. Background of Related Art
Laser-based instruments are becoming increasingly accepted in the medical field for use in minimally invasive procedures such as laser laparoscopy. For example, laser therapy is a widely accepted modality for tissue ablation procedures. Laser-based instruments are known to utilize fiber optic cables to deliver laser energy from the laser light source to targeted tissue.
Fiber optic cables are composed of one or more transparent glass or plastic fibers through which light is efficiently conducted with minimal loss. The light-conducting fibers, called the core, are encased in a second medium, called the cladding layer, which has an index of refraction lower than that of the core to provide total internal reflection of the rays propagating though the core. That is, light traveling through the fiber bounces at shallow angles and stays completely within the fiber because light hits the interface between the core and cladding at an angle less than the critical angle. At these angles, light does not pass through to the second medium, but rather, continues reflecting within the core until it reaches the terminus, or end of the fiber.
A surgeon who performs procedures using existing laser-based instruments is often challenged with non-uniform temperature distribution, because laser dispersion through the fiber terminus radiates from a point source at the instrument tip in a generally conical pattern, causing the temperature at the tip to increase rapidly to 800° C.-1,300° C. while rapidly decreasing with distance from the tip. Such wide temperature variations may have drawbacks. For example, the tendency for the temperature to decrease with distance from the fiber tip may unnecessarily complicate vascular ablation procedures.